Zoology and wildlife conservation

Uncoupling of the molecular 'fence' and paracellular 'gate' functions in epithelial tight junctions

Article Abstract:

The gate and fence functions of intercellular tight junctions can be separated by cell energy depletion. The gate function is that which determines transepithelial resistance to ions and non-electrolyte permeability. The fence function prevents the diffusion of lipids and proteins. Depletion of cell ATP was found to eliminate the gate function without changing the fence function. Therefore, molecular models which have attempted to explain both by a single mechanism involving strands of particles must be amended. The functional difference may result from two kinds of molecular contacts in the strands.

The signalling by wingless, the Drosophila Wnt-1 homologue, entails the activity of Armadillo, the homologue of vertebrate beta-catenin, at the adherens junction. Although both homologues signal different activities, either one can be used to control cell fate specification or cell-cell adhesion. Using full-length Drosophila E-cadherin and a dominant-negative truncated form, it was discovered that overexpression of either construct simulates wingless phenotypes.

Smells, brains and hormones

Article Abstract:

A common belief is that in mammals pheromones are detected only by a specialized sensor in the nose known as the vomeronasal organ, and that the main olfactory epithelium, which lines the nasal cavity is responsible only for sensing common odors. In mammals, female mating and reproductive behavior are controlled by a group of neurons in the hypothalamus, the brain's chief hormonal, or endocrine, control center.